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Background: There is increasing need for evidence-based data on reproduction for women with multiple sclerosis (MS). First-trimester (first 13 weeks) miscarriages are relatively common in the general population. It is therefore important to have information on the frequency with which this occurs in women with MS., Methods: The Canadian Multiple Sclerosis Pregnancy Study (CANPREG-MS) is a prospective study on women with MS who are pregnant or actively trying to conceive. As far as we are aware, this is the first study on miscarriages for this population that takes into account each woman's entire pregnancy history (i.e. before and after the MS diagnosis as well as during enrollment in CANPREG-MS)., Results: There were 208 pregnancies during the study and 36 resulted in first-trimester miscarriage for a rate of 17.31%, within the expected range of 15%-20% for the general population., Conclusions: CANPREG-MS provides real world data that there does not appear to be an increase in first-trimester miscarriages for women with MS. This information will be helpful to women with MS and their healthcare providers.

Objective: To evaluate the impact of temporal increase of female to male (F:M) sex ratio for persons with multiple sclerosis (MS) on the familial risk (empiric recurrence risks or RRs) for biological relatives of affected individuals., Methods: Detailed family histories were systematically obtained from people with MS attending the University of British Columbia Hospital MS Clinic. The study cohort was born in 1970 or more recently. Data were collected from 1 September 2015 to 31 January 2019. The study was designed to allow only one proband per family. Age-corrected RRs for biological relatives of probands were calculated based on a modification of the maximum-likelihood approach., Results: Data analyses were possible for 746 unique probands (531 females; 215 males) and 19,585 of their biological relatives. RRs were temporally impacted., Conclusion: Both genetic sharing and environmental factors are important in determining RRs. It appears that there is an increase in MS risk due to environmental factors in later life (i.e. not shared family environment). Environmental exposures in genetically predisposed individuals might be driving the MS risk. The increase in F:M ratio of RRs for sisters/brothers of female probands over time is likely due to environmental differences.

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system characterized by myelin loss and neuronal dysfunction. Although the majority of patients do not present familial aggregation, Mendelian forms have been described. We performed whole-exome sequencing analysis in 132 patients from 34 multi-incident families, which nominated likely pathogenic variants for MS in 12 genes of the innate immune system that regulate the transcription and activation of inflammatory mediators. Rare missense or nonsense variants were identified in genes of the fibrinolysis and complement pathways (PLAU, MASP1, C2), inflammasome assembly (NLRP12), Wnt signaling (UBR2, CTNNA3, NFATC2, RNF213), nuclear receptor complexes (NCOA3), and cation channels and exchangers (KCNG4, SLC24A6, SLC8B1). These genes suggest a disruption of interconnected immunological and pro-inflammatory pathways as the initial event in the pathophysiology of familial MS, and provide the molecular and biological rationale for the chronic inflammation, demyelination and neurodegeneration observed in MS patients., Competing Interests: The authors have declared that no competing interests exist.

The implementation of exome sequencing technologies has started to unravel the genetic etiology of familial multiple sclerosis (MS). A homozygote p.G587S mutation in NLRP1 has been suggested as potentially causative for the onset of MS in an affected sibling pair, who later developed malignant melanoma. To validate the proposed role of recessive NLRP1 mutations in the pathological mechanisms of MS, we examined exome sequencing data from 326 MS patients from Canada for the identification of NLRP1 missense and nonsense variants. This analysis did not identify the previously described p.G587S mutation; however, three patients with potential NLRP1 compound heterozygote mutations were observed. Haplotype and segregation analyses indicate that the variants observed in these patients were inherited in cis, and do not segregate with disease within families. Thus, the analysis of MS patients from Canada failed to identify potentially pathogenic mutations in NLRP1, including the previously described p.G587S mutation. Further studies are necessary to confirm a role of NLRP1 in the pathophysiology of MS.

The genetic contribution to clinical outcomes for multiple sclerosis (MS) has yet to be defined. We performed exome sequencing analysis in 100 MS patients presenting opposite extremes of clinical phenotype (discovery cohort), and genotyped variants of interest in 2016 MS patients (replication cohort). Linear and logistic regression analyses were used to identify significant associations with disease course, severity and onset. Our analysis of the discovery cohort nominated 38 variants in 21 genes. Replication analysis identified PSMG4 p.W99R and NLRP5 p.M459I to be associated with disease severity (p=0.002 and 0.008). CACNA1H p.R1871Q was found associated with patients presenting relapsing remitting MS at clinical onset (p=0.028) whereas NLRP5 p.M459I and EIF2AK1 p.K558R were associated with primary progressive disease (p=0.031 and 0.023). In addition, PSMG4 p.W99R and NLRP5 p.R761L were found to correlate with an earlier age at MS clinical onset, and MC1R p.R160W with delayed onset of clinical symptoms (p=0.010-0.041)., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Genetic variants in the purinergic receptors P2RX4 and P2RX7 have been shown to affect susceptibility to multiple sclerosis (MS). In this study, we set out to evaluate whether rare coding variants of major effect could also be identified in these purinergic receptors. Sequencing analysis of P2RX4 and P2RX7 in 193 MS patients and 100 controls led to the identification of a rare three variant haplotype (P2RX7 rs140915863:C>T [p.T205M], P2RX7 rs201921967:A>G [p.N361S], and P2RX4 rs765866317:G>A [p.G135S]) segregating with disease in a multi-incident family with six family members diagnosed with MS (logarithm of odds = 3.07). Functional analysis of this haplotype in HEK293 cells revealed impaired P2X7 surface expression (P < 0.01), resulting in over 95% inhibition of adenosine triphosphate (ATP)-induced pore function (P < 0.001) and a marked reduction in phagocytic ability (P < 0.05). In addition, transfected cells showed 40% increased peak ATP-induced inward current (P < 0.01), and a greater Ca 2+ response to the P2X4 135S variant compared with wild type (P < 0.0001). Our study nominates rare genetic variants in P2RX4 and P2RX7 as major genetic contributors to disease, further supporting a role for these purinergic receptors in MS and the disruption of transmembrane cation channels leading to impairment of phagocytosis as the pathological mechanisms of disease., (© 2017 Wiley Periodicals, Inc.)

Several single-gene disorders with clinical and radiological characteristics similar to those observed in multiple sclerosis (MS) patients have been described. To evaluate whether this phenotypic overlap can be ascribed to a common genetic etiology, 28 genes known to present pathogenic mutations for 24 of these disorders were sequenced in 270 MS patients. All identified variants were genotyped in 2131 MS cases and 830 healthy controls, and those exclusively observed in patients were assessed for segregation within families. This analysis identified 9 rare variants in 6 genes segregating with disease in 13 families. Four different mutations were identified in CYP27A1, including a reported pathogenic mutation for cerebrotendinous xanthomatosis (p.R405W), which was observed in six patients from a multi-incident family, three diagnosed with MS, two with an undefined neurological disease and one seemingly healthy. A LYST p.V1678A and a PDHA1 p.K387Q mutation were both observed in five MS patients from three separate multi-incident families. In addition, CLCN2 p.V174G, GALC p.D162E and POLG p.R361G were each identified in two MS patients from one family. This study suggests a shared genetic etiology between MS and the characterized single-gene disorders, and highlights cholesterol metabolism and the synthesis of oxysterols as important biological mechanisms for familial MS.

Multiple sclerosis (MS) is a prevalent neurological disease of complex etiology. Here, we describe the characterization of a multi-incident MS family that nominated a rare missense variant (p.G420D) in plasminogen (PLG) as a putative genetic risk factor for MS. Genotyping of PLG p.G420D (rs139071351) in 2160 MS patients, and 886 controls from Canada, identified 10 additional probands, two sporadic patients and one control with the variant. Segregation in families harboring the rs139071351 variant, identified p.G420D in 26 out of 30 family members diagnosed with MS, 14 unaffected parents, and 12 out of 30 family members not diagnosed with disease. Despite considerably reduced penetrance, linkage analysis supports cosegregation of PLG p.G420D and disease. Genotyping of PLG p.G420D in 14446 patients, and 8797 controls from Canada, France, Spain, Germany, Belgium, and Austria failed to identify significant association with disease (P = 0.117), despite an overall higher prevalence in patients (OR = 1.32; 95% CI = 0.93-1.87). To assess whether additional rare variants have an effect on MS risk, we sequenced PLG in 293 probands, and genotyped all rare variants in cases and controls. This analysis identified nine rare missense variants, and although three of them were exclusively observed in MS patients, segregation does not support pathogenicity. PLG is a plausible biological candidate for MS owing to its involvement in immune system response, blood-brain barrier permeability, and myelin degradation. Moreover, components of its activation cascade have been shown to present increased activity or expression in MS patients compared to controls; further studies are needed to clarify whether PLG is involved in MS susceptibility., (Copyright © 2016 Sadovnick et al.)

Oxysterols produced by CH25H during cholesterol metabolism have been shown to play an important role in the immune response. In this study we report the genetic characterization of CH25H in patients diagnosed with multiples sclerosis (MS) or neuromyelitis optica (NMO), for the identification of genetic variants affecting disease susceptibility and course. Exome analysis in 212 MS and 14 NMO patients identified a rare CH25H p.Q17H mutation in two NMO patients of Asian ancestry. In addition, association analysis of common CH25H variants identified a nominally significant association with MS patients presenting a clinical course consistent with primary progressive disease., Competing Interests: The authors declare that they have no conflict of interest., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Global variation in the incidence of multiple sclerosis (MS) is generally ascribed to differences in genetic and environmental risk factors. Here we investigate temporal trends in the incidence of MS and related disorders in British Columbia, Canada, from 1986 to 2010, focusing particularly on the Asian ethnic subpopulation., Methods: A longitudinal database was screened to identify newly diagnosed cases of MS and related disorders, including neuromyelitis optica and clinically isolated syndromes. Age-standardized, sex-specific mean annual incidence was calculated for the Asian and non-Asian population of British Columbia for 5-year intervals from 1986 to 2010. Temporal changes and cohort differences in incidence rates and demographic characteristics were evaluated., Results: During this period, the incidence of MS and related disorders in the non-Asian population remained relatively unchanged, from 10.41 (95% confidence interval [CI]: 9.87-10.97) to 9.91 (95% CI: 9.46-10.39) per 100,000 (p=0.167). In contrast, incidence in the Asian population doubled during the same period. This increase was driven by a precipitous rise in the incidence of MS in females from 0.71 (95% CI: 0.01-1.50) to 2.08 (95% CI: 1.43-2.91) per 100,000 (p=0.004), including both Canadian-born and immigrant Asians. The incidence of neuromyelitis optica did not change significantly during this period., Conclusions: The incidence of MS may be increasing among females in the Asian ethnic population of British Columbia.

Background: There is a well-documented increase in the risk of multiple sclerosis (MS) when migrating from a region of low prevalence to one of high prevalence., Objective: We present here an investigation of MS prevalence and candidate environmental and genetic risk factors among Iranian immigrants to British Columbia (BC), Canada., Methods: MS cases of Iranian ancestry were ascertained from a population-based Canadian study. We collected blood samples for genetic and serological analyses, and administered a personal history questionnaire to the cases., Results: The crude prevalence of MS in this population of Iranian ancestry was 287/100,000 (95% CI: 229 - 356/100,000). MS cases were more likely to have a history of infectious mononucleosis (odds ratio (OR) = 7.5; p = 0.005) and smoking (OR = 17.0; p < 0.0001), as compared to healthy controls from previous studies in Iran. Cases were also more likely than controls to have been born between April and September (OR = 2.1; p = 0.019)., Conclusion: The prevalence of MS among Iranian immigrants to Canada is greater than the overall prevalence of MS in Iran by a factor of at least four, and is similar to that recently observed among Iranian immigrants in other western nations. No major genetic susceptibility variants were identified, suggesting the environment in Canada may be what is increasing the risk of MS in this population., (© The Author(s) 2014.)

Background: Chronic cerebrospinal venous insufficiency has been proposed as a unique combination of extracranial venous blockages and haemodynamic flow abnormalities that occurs only in patients with multiple sclerosis and not in healthy people. Initial reports indicated that all patients with multiple sclerosis had chronic cerebrospinal venous insufficiency. We aimed to establish the prevalence of venous narrowing in people with multiple sclerosis, unaffected full siblings, and unrelated healthy volunteers., Methods: We did an assessor-blinded, case-control, multicentre study of people with multiple sclerosis, unaffected siblings, and unrelated healthy volunteers. We enrolled the study participants between January, 2011 and March, 2012, and they comprised 177 adults: 79 with multiple sclerosis, 55 siblings, and 43 unrelated controls, from three centres in Canada. We assessed narrowing of the internal jugular and azygous veins with catheter venography and ultrasound criteria for chronic cerebrospinal venous insufficiency proposed by Zamboni and colleagues. Catheter venography data were available for 149 participants and ultrasound data for 171 participants., Findings: Catheter venography criteria for chronic cerebrospinal venous insufficiency were positive for one of 65 (2%) people with multiple sclerosis, one of 46 (2%) siblings, and one of 32 (3%) unrelated controls (p=1·0 for all comparisons). Greater than 50% narrowing of any major vein was present in 48 of 65 (74%) people with multiple sclerosis, 31 of 47 (66%) siblings (p=0·41 for comparison with patients with multiple sclerosis), and 26 of 37 (70%) unrelated controls (p=0·82). The ultrasound criteria for chronic cerebrospinal venous insufficiency were fulfilled in 35 of 79 (44%) participants with multiple sclerosis, 17 of 54 (31%) siblings (p=0·15 for comparison with patients with multiple sclerosis) and 17 of 38 (45%) unrelated controls (p=0·98). The sensitivity of the ultrasound criteria for detection of greater than 50% narrowing on catheter venography was 0·406 (95% CI 0·311-0·508), and specificity was 0·643 (0·480-0·780)., Interpretation: This study shows that chronic cerebrospinal venous insufficiency occurs rarely in both patients with multiple sclerosis and in healthy people. Extracranial venous narrowing of greater than 50% is a frequent finding in patients with multiple sclerosis, unaffected siblings, and unrelated controls. The ultrasound criteria are neither sensitive nor specific for narrowing on catheter venography. The significance of venous narrowing to multiple sclerosis symptomatology remains unknown., Funding: MS Society of Canada, Saskatoon City Hospital Foundation, Lotte and John Hecht Memorial Foundation, Vancouver Coastal Health Foundation, and the Wolridge Foundation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Genetic and environmental factors have important roles in multiple sclerosis (MS) susceptibility. Several studies have shown an association between smoking and MS risk. Here, in a population-based Canadian cohort, we investigate the relationship between personal and maternal smoking exposure and the risk of MS. Using the longitudinal Canadian database, 3,157 MS cases and 756 spouse controls were administered questionnaires on active and passive smoking history. Mothers of cases and controls were also asked about their smoking exposure during pregnancy. The MS cases were more likely to have smoked than spouse controls (odds ratio 1.32, 95 % confidence interval 1.10-1.60, p = 0.003). This association was driven by an excess of ever-smokers in male MS cases. No association was seen with maternal active or passive smoking exposure during pregnancy. Ever-smoking is associated with increased MS risk in males. Further work is needed to understand the mechanism underlying this association.

Objective: To determine whether different health care systems may affect reproductive decision-making among patients with Multiple Sclerosis (MS), we describe the reproductive practices and attitudes of Canadian MS patients ascertained from the multidisciplinary MS Clinic at Hôpital Notre-Dame in Montreal, Quebec (NDMSC), in comparison to those of matched American self-registrants from the database of the North American Research Committee on Multiple Sclerosis (NARCOMS)., Methods: A total of 665 self-administered questionnaires on reproductive practices were sent out to eligible attendees attending the NDMSC. The short questionnaires were completed and returned to the authors in an anonymous format for analysis., Results: A total of 459 completed questionnaires were returned. The majority of NDMSC respondents (72.5%) and NARCOMS subset (75.2% females), did not encounter a pregnancy following diagnosis of MS. The most common MS-related reason for this decision was "symptoms interfering with parenting" (75.0% for the NDMSC, 72.6% for the NARCOMS). The most commonly reported non-MS-related reason was "a completed family" by the time of diagnosis in both the NDMSC and NARCOMS subset (58.0%, 40.4%, respectively). Concerns about financial issues both related and unrelated to MS were also commonly reported by males and females in both cohorts but significantly more so among the NARCOMS participants., Conclusion: These results indicate that reproductive decisions of MS patients are highly affected by their illness and its associated disability, regardless of the available health care program. Health care providers should discuss their patients' reproductive needs and perceptions to help them make more informed decisions.

Objective: Pregnancy has a well documented effect on relapse risk in multiple sclerosis (MS). Prospective studies have reported a significant decline by two-thirds in the rate of relapses during the third trimester of pregnancy and a significant increase by two-thirds during the first 3 months postpartum. However, it is unclear as to whether there are any long term effects on disability., Methods: Data were collated from clinical records and family histories systematically collected from the University of British Columbia MS Clinic., Results: Clinical and term pregnancy data were available from 2105 female MS patients. MS patients having children after MS onset took the longest time to reach an Expanded Disability Status Scale (EDSS) score of 6 (mean 22.9 years) and patients having children before MS onset were the quickest (mean 13.2 years). However, these effects were not related to term pregnancy and were fully accounted for by age of MS onset., Conclusions: Pregnancy had no effect on the time to reach an EDSS score 6. As MS predominantly affects women of childbearing age, women with MS can be reassured that term pregnancies do not appear to have any long term effects on disability.

The precise aetiology of multiple sclerosis (MS) is yet to be conclusively determined, but both genes and environment and interactions thereof are important. It has been suggested that early life child exposure influences MS susceptibility. Here, in a population-based cohort, we investigated whether infant day care attendance influences the subsequent risk to develop MS. We identified 379 MS index cases and 101 spousal controls, all of whom were a single child (i.e. they had no biological sibs, half-sibs, step-sibs, adopted sibs) from the Canadian Collaborative Project on Genetic Susceptibility to MS (CCPGSMS). Frequency of infant day care attendance was compared for index cases and controls and the results were not statistically significant. Exposure to other infants during early childhood thus does not appear to be a risk factor for MS., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: There is a strong maternal parent-of-origin effect in determining susceptibility to multiple sclerosis (MS). One hypothesis is that an abnormal intrauterine milieu leading to impaired fetal development could plausibly also result in increased susceptibility to MS. A possible marker for this intrauterine insult is the presence of a non-fatal congenital anomaly., Methods: We investigated whether or not congenital anomalies are associated with MS in a population-based cohort. We identified 7063 MS index cases and 2655 spousal controls with congenital anomaly information from the Canadian Collaborative Project on Genetic Susceptibility to MS (CCPGSMS)., Results: The frequency of congenital anomalies were compared between index cases and controls. No significant differences were found., Conclusions: Congenital anomalies thus do not appear to be associated with MS. However, we did not have complete data on types and severity of congenital anomalies or on maternal birth history and thus this study should be regarded as preliminary.

Autoimmune mechanisms are thought to have a major role in the pathogenesis of multiple sclerosis (MS) and vitamin D is hypothesised to contribute to disease susceptibility. Cow's milk allergy (CMA) is a common childhood allergy arising from an immune system imbalance and can also lead to vitamin D deficiency due to dairy food avoidance. Here, we investigated whether or not CMA influences the subsequent risk to develop MS in a population-based cohort. We identified 6638 MS index cases and 2509 spousal controls with CMA information from the Canadian Collaborative Project on Genetic Susceptibility to MS (CCPGSMS). Frequency of CMA was compared between index cases and controls. No significant differences were found. Childhood CMA thus does not appear to be a risk factor for MS., (Copyright 2009 Elsevier B.V. All rights reserved.)

Background: Genetic and environmental factors have important roles in multiple sclerosis (MS) susceptibility. A clear parent-of-origin effect has been shown in several populations. Advanced maternal age has been shown to be associated with adverse outcomes in offspring including chromosomal abnormalities. Advanced paternal age is associated with a number of adult onset disorders including schizophrenia and bipolar disorder. In a population-based Canadian cohort, we investigated whether there is any difference in parental age at birth for MS index cases compared to spouse controls., Methods: Using the longitudinal Canadian database, we identified 5,681 MS index cases and 1,249 spouse controls with complete information on parental dates of birth, thereby allowing a calculation of the maternal and paternal ages at the birth of their children (MS index cases and spouse controls)., Results: No significant difference in maternal or paternal age at birth was found (average MS index case maternal age at birth = 27.3 years, average spouse control maternal age at birth = 27.0 years, p = 0.13; average MS index case paternal age at birth = 30.7 years, average spouse control paternal age at birth = 30.2 years, p = 0.37)., Conclusions: Parental age at birth is not associated with susceptibility to MS., (Copyright 2009 S. Karger AG, Basel.)

Multiple sclerosis (MS) is a complex neurological trait. Allelic variation in the MHC class II region exerts the single strongest effect on MS genetic risk. The clinical onset of the disease is extremely variable, and can range from the first to the ninth decade of life. Epidemiological studies have suggested a modest genetic component to the age of onset (AO) of MS. Previous studies have shown that HLA-DRB1*1501 may be associated with a younger AO. Here, we sought to uncover any effect of HLA-DRB1*1501 on the AO of MS in a large Canadian cohort. A total of 1816 MS patients were genotyped for HLA-DRB1. Patients carrying HLA-DRB1*1501 were shown to have a small, but significantly lower, AO than patients without the allele (P=0.03). HLA-DRB1*1501 was also shown to reduce the mean AO in both progressive and relapsing forms of the disease. An investigation of parent-of-origin effects indicated that the lower AO for HLA-DRB1*1501 patients arises from maternally transmitted HLA-DRB1*1501 haplotypes (maternal HLA-DRB1*1501 mean AO=28.4 years, paternal=30.3 years; P=0.009). HLA-DRB1*1501 exerts a modest, but significant effect on the AO of all forms of MS. Parent-of-origin effects at the MHC are further implicated in MS disease pathogenesis.

The ages of onset in multiple sclerosis cases span more than 7 decades. Data are presented for affected relative pairs from a Canadian population base of 30,000 multiple sclerosis index cases (1993-2008). The effects of genetic sharing, parent of origin, intergenerational versus collinear differences, and gender on the ages of onset were evaluated in the following concordant pairs: monozygotic twins (n = 29), dizygotic twins (n = 10), siblings (n = 614), first cousins (n = 405), half siblings (n = 29), parent/child (n = 285), and aunt/uncle/niece/nephew (avunculars) (n = 289). Fisher's z test assessed intraclass correlation (r) for ages of onset. Correlations for monozygotic twins, dizygotic twins, full siblings, and first cousins were 0.60, 0.54, 0.20, and 0.10, respectively. Dizygotic twins resembled monozygotic twins more than siblings. The age-of-onset correlation for maternal half siblings (r = 0.37) was higher than that for paternal half siblings (r = 0.26), consistent with other observations suggesting an intrauterine environmental effect on multiple sclerosis risk. Intergenerational comparisons are complicated by substantial increases of multiple sclerosis incidence over time. Genetic loading (familial vs. sporadic cases) did not generally influence the age of onset, but correlation of age of onset in multiple sclerosis relative pairs was proportional to genetic sharing. A maternal parent-of-origin effect on the age of onset in collinear generations was suggested.

Background: Genetic and environmental factors have important roles in multiple sclerosis (MS) susceptibility. Several studies have attempted to correlate exposure to viral illness with the subsequent development of MS. Here in a population-based Canadian cohort, we investigate the relationship between prior clinical infection or vaccination and the risk of MS., Methods: Using the longitudinal Canadian database, 14,362 MS index cases and 7,671 spouse controls were asked about history of measles, mumps, rubella, varicella and infectious mononucleosis as well as details about vaccination with measles, mumps, rubella, hepatitis B and influenza vaccines. Comparisons were made between cases and spouse controls., Results: Spouse controls and stratification by sex appear to correct for ascertainment bias because with a single exception we found no significant differences between cases and controls for all viral exposures and vaccinations. However, 699 cases and 165 controls reported a history of infectious mononucleosis (p < 0.001, corrected odds ratio 2.06, 95% confidence interval 1.71-2.48). Females were more aware of disease history than males (p < 0.001)., Conclusions: The data further confirms a reporting distortion between males and females. Historically reported measles, mumps, rubella, varicella and vaccination for hepatitis B, influenza, measles, mumps and rubella are not associated with increased risk of MS later in life. A clinical history of infectious mononucleosis is conspicuously associated with increased MS susceptibility. These findings support studies implicating Epstein-Barr virus in MS disease susceptibility, but a co-association between MS susceptibility and clinically apparent infectious mononucleosis cannot be excluded.

Background: Genetic and environmental factors have important roles in multiple sclerosis (MS) susceptibility. A clear parent of origin effect has been shown in several populations, perhaps resulting from factors operating during gestation. Preterm birth (birth at less than 37 weeks gestational age) has been shown to result in long-term health problems, including impaired neurological development. Here, in a population-based cohort, we investigate whether preterm birth increases the risk to subsequently develop MS., Methods: We identified 6585 MS index cases and 2509 spousal controls with preterm birth information from the Canadian Collaborative Project on Genetic Susceptibility to MS. Rates of individuals born preterm were compared for index cases and controls., Results: There were no significant differences between cases and controls with respect to preterm births. 370 (5.6%) MS index cases and 130 (5.2%) spousal controls were born preterm, p = 0.41., Conclusion: Preterm birth does not appear to contribute to MS aetiology. Other factors involved in foetal and early development need to be explored to elucidate the mechanism of the increased risk conferred by the apparent maternal effect.

Background: Genetic and environmental factors have important roles in multiple sclerosis (MS) susceptibility. A clear maternal effect has been shown in several population-based studies. This parent-of-origin effect could result from factors operating during gestation. It has been shown that a low birth weight increases the risk of several adult-onset diseases. In a population-based Canadian cohort, we investigated whether there is any difference in birth weight for MS index cases compared to spousal controls., Methods: Using the longitudinal Canadian database, we identified 6,188 MS index cases and 1,640 spousal controls with birth weight information. Additionally, data were available on 164 discordant MS twins. The birth weight was compared between index cases and controls as well as for twin pairs., Results: When stratifying by sex, no significant difference in birth weight was found (average female index case birth weight = 7.23 pounds, average female control birth weight = 7.19 pounds, p = 0.48; average male index case birth weight = 7.56 pounds, average male control birth weight = 7.55 pounds, p = 0.92). Furthermore, there was no difference in birth weight between affected and unaffected twins (average affected twin weight = 5.46 pounds, average unaffected twin weight = 5.44 pounds, p =0.85)., Conclusions: The maternal effect in MS aetiology does not appear to act through a route that has an influence on birth weight. As birth weight is a relatively poor marker of fetal development, other factors involved in fetal and early development need to be explored to elucidate the mechanism of the increased MS risk conferred maternally., (2008 S. Karger AG, Basel.)

Objective: To determine the incidence of multiple sclerosis (MS) in a longitudinal surveillance over 35 years and to estimate the prevalence rate in Saskatoon, Saskatchewan, on January 1, 2005., Methods: A population-based registry was established in 1969, and identification of cases continued to 2005, from medical records, physicians, neurologists, community and provincial resources. A modified classification of Allison and Millar and the Schumacher diagnostic criteria were originally applied, and patients with definite and probable MS were included. The rates were age- and sex-adjusted to the US, European, and world 2000 populations., Results: From 1970 to 2004, there were 558 incidence cases identified, 402 women and 156 men, for a sex ratio of 2.6:1 The average annual incidence rate was 9.5 in 100,000 (95% CI 8.8 to 10.4) and was stable over the three decades. The innate risk or residence at onset rate was 197 in 100,000 (95% CI 170 to 226). The crude prevalence rate for the living 587 cases on January 1, 2005, was 298.3 in 100,000 (95% CI 274.7 to 323.6)., Conclusions: The incidence and prevalence rates adjusted to the standardized populations were statistically higher than the longitudinal European studies and similar to North American studies. Our incidence study confirms the high risk of multiple sclerosis (MS) in Saskatoon, and these rates seem to be stable over the past 35 years. The high crude prevalence rate results from an accumulation of incidence and nonresident cases over time. Long-term follow-up studies and comparison with standardized populations are recommended to estimate reliable incidence and the true risk of MS in the world.

Background: Evidence of an association between multiple sclerosis (MS) and other autoimmune diseases would substantiate the hypothesis that MS is an autoimmune disease, and implicate a common mechanism. We aimed to investigate and compare the rate of autoimmune disease in MS patients, in their first-degree relatives, and in their unrelated spouses., Methods: We used data from a national, multicentre, population-based sample to investigate the rate of autoimmune disease in 5031 MS patients, 30 259 of their first-degree relatives, and 2707 spousal controls. We asked patients and controls whether they had any of ten autoimmune diseases: Crohn's disease, ulcerative colitis, rheumatoid arthritis, type 1 diabetes, psoriasis, pernicious anaemia, systemic lupus erythematosus, autoimmune thyroid disease, vitiligo, and myasthenia gravis. MS probands were also asked whether their first-degree relatives had Crohn's disease, ulcerative colitis, rheumatoid arthritis, or type 1 diabetes., Findings: After correction for age and sex, we did not identify any increased risk of autoimmune diseases in MS patients compared with their spousal controls (odds ratio [OR]=1.07, 95% CI 0.86-1.23, chi(2)=0.47, p=0.49), or in the first-degree relatives of MS probands compared with controls (OR=0.89, 0.63-1.17, chi(2)=1.11, p=0.29). However, the reported frequency of autoimmune diseases did differ according to the sex of the interviewee (female vs male patients chi(2)=92.2, p<0.0001; female vs male spousal controls chi(2)=87.1, p<0.0001). MS patients had slightly higher rates of thyroid disease and pernicious anaemia than did controls, which is consistent with MHC associations for these diseases, but this effect disappeared when results were adjusted for sex. For eight other diseases the rates were similar in MS patients and controls. Families with multiple cases of MS were no more likely to report autoimmune diseases than families with single MS cases., Interpretation: When data were adjusted for sex, no excess of common autoimmune diseases could be identified in MS patients or their families, including multicase pedigrees. Our results suggest that women are more aware of family medical histories than men, which emphasises the potential for ascertainment bias in unstratified data for a sex-limited disease. Family histories should thus be taken from male patients in the presence of a spouse.

Background: Incidence of multiple sclerosis is thought to be increasing, but this notion has been difficult to substantiate. In a longitudinal population-based dataset of patients with multiple sclerosis obtained over more than three decades, we did not show a difference in time to diagnosis by sex. We reasoned that if a sex-specific change in incidence was occurring, the female to male sex ratio would serve as a surrogate of incidence change., Methods: Since environmental risk factors seem to act early in life, we calculated sex ratios by birth year in 27 074 Canadian patients with multiple sclerosis identified as part of a longitudinal population-based dataset., Findings: The female to male sex ratio by year of birth has been increasing for at least 50 years and now exceeds 3.2:1 in Canada. Year of birth was a significant predictor for sex ratio (p<0.0001, chi(2)=124.4; rank correlation r=0.84)., Interpretation: The substantial increase in the female to male sex ratio in Canada seems to result from a disproportional increase in incidence of multiple sclerosis in women. This rapid change must have environmental origins even if it is associated with a gene-environment interaction, and implies that a large proportion of multiple sclerosis cases may be preventable in situ. Although the reasons why incidence of the disease is increasing are unknown, there are major implications for health-care provision because lifetime costs of multiple sclerosis exceed pound1 million per case in the UK.

Background: Genetic epidemiological studies suggest both genetic and environmental factors have a role in multiple sclerosis (MS). Environmental effects are strongly suggested from geographical gradients, migration data, and discordance rates in twins. In epidemiological studies, risk of MS in offspring of small families and in those with an early birth-order position has been reported and interpreted in the context of the hygiene hypothesis, which is that infections at an early age, introduced by older siblings, are protective. We aimed to study the effect of birth order on MS risk., Methods: A longitudinal, population-based sample of individuals with MS and their healthy siblings were identified from the Canadian Collaborative Project on Genetic Susceptibility to MS. Data were grouped according to single (simplex) or multiple (multiplex) siblings with MS in a sibship. Separate analyses were done for each sibship size., Findings: We studied 10 995 individuals with MS and 26 336 healthy siblings, and found no relation between MS risk and birth-order position. In simplex sibships of at least seven siblings, slightly more siblings who were born late in the birth order had MS; the same was found for the first-born sibling with MS in a multiplex sibship. Siblings with MS were slightly younger (p<0.0001) than those without MS, contrary to the expected age at onset bias., Interpretation: These findings do not support the hygiene hypothesis and could be due to a cohort effect resulting from increasing MS incidence. Birth order has no effect on MS risk in most families, and there is no support for the hypothesis that having older siblings protects against MS.

The etiopathogenesis of multiple sclerosis (MS) remains unclear. However, genetic factors are believed to be important in disease susceptibility. A methodological approach is presented for a population-based study aimed at investigating MS familial incidence and patterns of familial clustering in Northern Sardinia, Italy, with a reported MS prevalence of 150/100,000 population. Patients with MS since 1965 to the present and known to the MS Register for the province of Sassari will be asked to provide genealogical, comorbid and demographic information. Statistical analyses of the familial risk for MS will depend on the completeness of MS 'age at onset' data for affected individuals and age at the time family history is obtained (or age at death) for unaffected family members., (Copyright 2003 S. Karger AG, Basel)

Background: There is increasing need for evidence-based data on reproduction for women with multiple sclerosis (MS). First-trimester (first 13 weeks) miscarriages are relatively common in the general population. It is therefore important to have information on the frequency with which this occurs in women with MS. Methods: The Canadian Multiple Sclerosis Pregnancy Study (CANPREG-MS) is a prospective study on women with MS who are pregnant or actively trying to conceive. As far as we are aware, this is the first study on miscarriages for this population that takes into account each woman's entire pregnancy history (i.e. before and after the MS diagnosis as well as during enrollment in CANPREG-MS). Results: There were 208 pregnancies during the study and 36 resulted in first-trimester miscarriage for a rate of 17.31%, within the expected range of 15%–20% for the general population. Conclusions: CANPREG-MS provides real world data that there does not appear to be an increase in first-trimester miscarriages for women with MS. This information will be helpful to women with MS and their healthcare providers. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the impact of temporal increase of female to male (F:M) sex ratio for persons with multiple sclerosis (MS) on the familial risk (empiric recurrence risks or RRs) for biological relatives of affected individuals. Methods: Detailed family histories were systematically obtained from people with MS attending the University of British Columbia Hospital MS Clinic. The study cohort was born in 1970 or more recently. Data were collected from 1 September 2015 to 31 January 2019. The study was designed to allow only one proband per family. Age-corrected RRs for biological relatives of probands were calculated based on a modification of the maximum-likelihood approach. Results: Data analyses were possible for 746 unique probands (531 females; 215 males) and 19,585 of their biological relatives. RRs were temporally impacted. Conclusion: Both genetic sharing and environmental factors are important in determining RRs. It appears that there is an increase in MS risk due to environmental factors in later life (i.e. not shared family environment). Environmental exposures in genetically predisposed individuals might be driving the MS risk. The increase in F:M ratio of RRs for sisters/brothers of female probands over time is likely due to environmental differences. [ABSTRACT FROM AUTHOR]

Objective: The objective of this prospective "real world" study is to gain insight into the different "roads to conception" that women with MS take as part of the prospective Canadian Multiple Sclerosis Pregnancy Study (CANPREG-MS). Methods: Participants are women with MS who are planning a pregnancy. Data cut-off for analyses was April 30, 2020. Results: We believe this is the first prospective National study of women with MS planning pregnancies. The data are for the first 44 women enrolled of whom 26 achieved pregnancy by cut-off date. Seven women used assisted reproductive technologies (ARTs); 6 stopped disease modifying therapy (DMT) against their neurologists' recommendations; 6 had an interruption(s) in trying to conceive due to MS relapses, MRI-detected inflammation, or limited "windows of opportunity" between DMT courses. Conclusion: The study illustrates the roads that women take to conception, even if they are on the same therapy and have similar clinical expression of MS. Advice given by treating neurologists on washout periods show discrepancies. This paper highlights the real problem that there is no definitive, international consensus on managing these women due to the lack of "real world" data and thus the goal of CANPREG-MS is to provide such real world data. [ABSTRACT FROM AUTHOR]

Background Studies have indicated an association between low Ultraviolet B (UVB) exposure and an increased risk of developing multiple sclerosis (MS). Few studies, however, have explored whether UVB exposure is associated with the age at MS symptom onset. Objective We investigated the potential association between cumulative early life ambient UVB exposure and age at MS onset, using satellite data to measure ambient UVB exposure. Methods Adult onset MS patients were selected from the University of British Columbia's MS genetic database (1980–2005). Patients’ places of residence from birth to age 18 years were geocoded (latitude and longitude) and assigned UVB values using NASA's Total Ozone Mapping Spectrometer (TOMS) dataset. Linear regression was used to explore the relationship between cumulative UVB exposure (measured for age periods 0–6, 7–12, 13–18, 0–12, and 0–18) and age at MS onset. Results 3226 patients were included in the analysis. Of these, 74% were female, with an overall mean symptom onset age of 33.3 years. At onset, a total of 2944 (91%) had a relapsing-remitting disease course, 254 (8%) had primary progressive and the disease course for 28 (1%) was unknown. No significant associations between cumulative early life ambient UVB exposure and age at MS onset were observed. Patient sex, MS phenotype, and immigration to Canada after age 18 were significantly associated with age of onset (p < 0.01). Conclusions Early life ambient UVB, as measured by satellite imagery, was not significantly associated with the age at MS onset. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigates the prevalence and genetic risk factors of multiple sclerosis (MS) among Iranian immigrants to British Columbia. Topics include the collection of blood samples for serological analyses and used questionnaire, the characteristics and causes of MS, and cases of MS patients with smoking history.

Background. A population-based prevalent cohort of 150 clinical definite multiple sclerosis (MS) cases (102 women; 48 men) ascertained on January 1,1977, Saskatoon, Saskatchewan, was found to have a familial rate of MS as 17.3%. Objectives. To determine the occurrence of familial MS cases and the frequency of MS among the biological relatives of the study cohort. Methods. The search for new familial cases MS affected relatives continued for 35 years until 2012. The natural history of the disease of sporadic cases is compared with that of the familial cases. SPSS V19 and Kaplan-Meier survival analysis were used for data analysis. Results. Of the 150 unrelated MS patients, 49 cases (32.7%) (36 women and 13 men) were reported of having at least one family member with MS. There were a total of 86 affected relatives, 26 (30.2%) first-degree relatives, 15 (17.4%) second-degree relatives, 20 (23.3%) third-degree relatives, and 25 (29.1%) distant relatives. The average age of MS onset for men with sporadic MS was 33.9 (SD = 10) years and 27.6 (SD = 8.4) years for familial cases and 29.3 (SD = 8.3) years and 26.8 (SD = 8.5) years for women. Conclusion. This 35-year longitudinal natural history study reveals a high frequency of cases with family members developing MS and supports a genetic influence in the etiology of MS. [ABSTRACT FROM AUTHOR]

The article presents a study on the demographic and clinical characteristics of multiple sclerosis (MS) among aboriginals in British Columbia (BC). The study involved patient information from the linked BC-wide MS clinical and genetics databases, and the identification of aboriginals through the database linkage augmented by physician and nurse recall. The result revealed a more rapid MS progression in aboriginals, as compared to non-aboriginals.

Summary Multiple sclerosis (MS) is an inflammatory disease characterized by myelin loss and neuronal dysfunction. Despite the aggregation observed in some families, pathogenic mutations have remained elusive. In this study, we describe the identification of NR1H3 p.Arg415Gln in seven MS patients from two multi-incident families presenting severe and progressive disease, with an average age at onset of 34 years. Additionally, association analysis of common variants in NR1H3 identified rs2279238 conferring a 1.35-fold increased risk of developing progressive MS. The p.Arg415Gln position is highly conserved in orthologs and paralogs, and disrupts NR1H3 heterodimerization and transcriptional activation of target genes. Protein expression analysis revealed that mutant NR1H3 (LXRA) alters gene expression profiles, suggesting a disruption in transcriptional regulation as one of the mechanisms underlying MS pathogenesis. Our study indicates that pharmacological activation of LXRA or its targets may lead to effective treatments for the highly debilitating and currently untreatable progressive phase of MS. [ABSTRACT FROM AUTHOR]

Summary Identifying rare genetic variants that drive the onset of disease is challenging, even before considering the additional genetic and environmental influences that likely exist in complex diseases. We recently published a study proposing a rare variant in the NR1H3 gene (p.R415Q, rs61731956) as responsible for the onset of multiple sclerosis (MS) in two multi-incident families ( Wang et al., 2016 ). This publication has generated much discussion, and fortunately the possibility to validate a finding or prove it spurious can occur rapidly in genetic studies. All novel discoveries must be replicated, and best efforts should be made to ensure that these replications use the appropriate samples and approach, and provide the correct interpretation of the results. This Matters Arising Response paper addresses the Minikel and MacArthur (2016) and The International Multiple Sclerosis Genetics Consortium (2016) Matters Arising papers, published concurrently in Neuron . [ABSTRACT FROM AUTHOR]